The present invention relates to a tube-incorporated tire which is comprised of a tire mounted around an outer periphery of a rim, and a tube which is accommodated in a space defined by the rim and the tire and which is formed with an air chamber to be filled with air and a sealant chamber filled with a sealant.
In a usual tube-incorporated tire, if a tube gets a punctured wound caused by a nail or the like, air in the tube is leaked from the punctured wound through a small clearance between the tire and the tube and via a nipple bore in the rim to the outside and, the tire becomes flat.
In view of the above circumstance, a tube-incorporated tire has been proposed in Japanese Patent Application Laid-open No.54-38007, in which the internal space in the tube is partitioned by a partition wall into an air chamber filled with air and a sealant chamber filled with a sealant. In this tube-incorporated tire, even if the tube gets a punctured wound by a nail or the like, such punctured wound can be repaired by the sealant filled in the sealant chamber, thereby preventing the leakage of air from the air chamber.
When the tube is set in the tire, the tube is deflated and mounted within the tire and then, air is filled into the air chamber to expand the air chamber. At that time, the volume of the air chamber in the tube is increased by the filling of the air and for this reason, in the tire with the inside of the tube divided into the air chamber and the sealant chamber, the partition wall is stretched by the increase in volume of the air chamber to generate a tension. If the partition wall gets a punctured wound in this state, the partition wall is intended to be contracted by such tension to compress the air chamber and hence, there is a possibility that the air in the air chamber is forced out through the punctured wound into the sealant chamber, where the air is incorporated into the sealant, resulting in a reduced sealing performance.
Accordingly, it is an object of the present invention to prevent the air in the air chamber from being incorporated into the sealant in the sealant chamber when the partition wall gets a punctured wound.
To achieve the above object, according to the present invention, there is provided a tube-incorporated tire comprising a tire mounted around an outer periphery of a rim, and a tube which is accommodated in a space defined by the rim and the tire and which is formed with an air chamber to be filled with air and a sealant chamber filled with a sealant, wherein the ratio of a length of an outer circumference of the tube in an air-filled state to that of the tube in an air-unfilled state is set in a range of 100% to 110%.
With the above arrangement, the ratio of the length of the contour of the tube in the air-filled state to that of the contour of the tube in the air-unfilled state is set in a range of 100% to 110%, and hence, when air is filled in the air chamber, the tension applied to the partition wall can be reduced. Therefore, even if the partition wall gets a punctured wound, the tendency for the partition wall to reduce the air chamber by the tension is lowered and as a result, it is difficult for the air in the air chamber to flow through the punctured wound into the sealant chamber. Thus, it is possible to avoid the incorporation of the air into the sealant to prevent a reduction in sealing performance.